Current collectors are an important part of rechargeable lithium-ion batteries (LIBs), which are bridges for internal and external circuits. Although positive and negative electrode materials are ever-changing, Al foils and Cu foils are still the most popular positive and negative current collectors in LIBs due to their high conductivity, proper electrochemical stability, and low cost. However, Al foil is susceptible to localized electrochemical anodic corrosion during long-term cycling, resulting in increased resistance, short circuits, and parasitic side reactions. To solve this problem, researchers use graphene films as conductive coatings and interfacial separators to improve the electrochemical corrosion resistance of aluminum foils. A multi-layered graphene film is directly grown on an aluminum foil for a commercial current collector by a plasma chemical vapor deposition method, and a multi-layered graphene film tightly attached to the aluminum foil has ion/molecular impermeability and can effectively block the anode electrode. The resulting Al3+ complexes with the anions and solvent molecules in the electrolyte. Therefore, graphene-coated aluminum foil can significantly improve its electrochemical corrosion resistance.
Recently, Prof. Peng Hailin and Academician Liu Zhongfan (co-corresponding authors) of the School of Chemistry and Molecular Engineering of Peking University have coated aluminum foil with low-temperature-grown graphene films to enhance their corrosion resistance in LiPF6 and LiTFSI electrolytes. In addition, compared with the original aluminum foil (LMO/PA), the LiMn2O4 battery uses a graphene-coated aluminum foil as a current collector (LMO/GA) to exhibit more excellent electrochemical performance. The long-term discharge capacity retention rate of LMO/GA, after 950 hours, can still reach the initial 91%, which is obviously higher than 75% of the LMO/PA battery, and the self-discharge rate is even lower. The research was published on Adv. Mater. as "Graphene-Armored Aluminum Foil with Enhanced Anticorrosion Performance as Current Collectors for Lithium-Ion Battery".
Figure 1. Schematic of anti-electrochemical corrosion of graphene-coated aluminum foil current collectors
Figure 2. Synthesis and Characterization of Graphene-coated Aluminum Foil by PECVD
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